In the powder metallurgy art various products are formed by pressing finely ground powders into a desired shape within a die cavity. According to one known procedure the metal powders are compacted in the die cavity at room temperature and the semi-dense compact is then removed from the die and heated to bond the powders into a unified mass. The heat bonding procedure is generally referred to as sintering.
By another procedure the pressing and sintering steps are combined in one operation in a preheated die.
Whichever of these or similar procedures is employed, means are required for delivering measured amounts of powder or particulate to a die cavity. Because many of the powdered materials are very heavy and dense, they have a marked tendency to self compact, making simple gravity feed methods inadequate and unsatisfactory. Shaking or vibrating a feed hopper is frequently employed for inducing flow of the particulate. This, however, is time consuming and inaccurate in delivering a measure weight or amount of materials to the die cavity.
In addition, shaking of the fine powders dislodges "fines" and dust from the powder which are then air borne to coat and contaminate the surrounding environs. Inasmuch as many of the powdered materials are frequently quite costly and in some cases toxic, the dust problem can represent a considerable economic loss unless recovered to say nothing of the health hazzard created by the dust. Consequently, relatively elaborate and costly dust recovery systems and personnel safety precaution, such as filtered masks are resorted to, by present day practice.